Use as_deref

Instead of this:

    foo.as_ref().map(|x| x.as_slice())

do this:

    foo.as_deref()

It's shorter and more to the point, and should thus be easier to
understand.

Found by clippy lint option_as_ref_deref:
https://rust-lang.github.io/rust-clippy/master/index.html#option_as_ref_deref

1 files changed, 1 insertions, 1 deletions

diff --git a/openpgp/src/packet/literal.rs b/openpgp/src/packet/literal.rs
index 29bfa187..14b98b38 100644
--- a/openpgp/src/packet/literal.rs
+++ b/openpgp/src/packet/literal.rs
@@ -110,7 +110,7 @@ impl Literal {
     /// only the literal data packet's body is protected, not the
     /// meta-data.  As such, this field should normally be ignored.
     pub fn filename(&self) -> Option<&[u8]> {
-        self.filename.as_ref().map(|b| b.as_slice())
+        self.filename.as_deref()
     }
 
     /// Sets the literal packet's filename field.